Why did the Egyptian say to David, "Swear to me by GOD that you won't kill me or hand me over to my master"?

1 Samuel 30:15

NKJV - 15 And David said to him, "Can you take me down to this troop?" So he said, "Swear to me by God that you will neither kill me nor deliver me into the hands of my master, and I will take you down to this troop.

I humbly submit that this nameless slave after being left in a field by his Amalekite master to die and then enduring the three long and painful days to death's door.
Had spent sometime around the Amalekite evening campfires and knew well their vile customs and ways toward perceived traitors or their enemies in general.
This discarded Egyptian was not only found, but was shown and received more mercy from total strangers than he received from his worldly master. 1 Samual 30:11
We're not told the exact time it took for him to recover his strength 1 Samual 30:12 but during this time he perceived that the character of his rescuers was far different, than that of the Amalekites.
He knew that any sworn pledge before God from these strangers was solid gold, and is akin to the current master card ad which is priceless.
And that David as their leader, unlike the current leaders of today would honor their pledge completely or die trying!
In the Lord's freedom to show mercy to those perishing before us.......warrior on

The young Egyptian boy was servant to one of the Amalekites, the people David was in pursuit of. David asked the young Egyptian boy if he would show him their location.
The Egyptian agreed to "rat out" the Amalekites location but with the following stipulation v.15 "..............And he said, Swear unto me by God, that thou wilt neither kill me, nor deliver me into the hands of my master, and I will bring thee down to this company."